Exemplary embodiments of the present invention relate to a device and a method for producing a three dimensional object through selective solidification of a powdery material by means of the application of energy.
Such devices and methods are known, for example, from German Patent documents DE 43 00 478 C1, DE 296 24 498 U1, and DE 10 2007 018 126 A1.
The following approaches are known for producing three dimensional objects using selective solidification by applying energy on a powdery material.
Either a powdery material is layered in a bed of powder and then selectively irradiated, for example, with electromagnetic radiation, so that the powdery material sinters at predetermined locations, and the three dimensional object is produced.
As an alternative, the powdery material can be applied in thin layers one after the other on a working surface and then can be solidified through the selective application of energy at locations, at which the powdery material is supposed to form a layer of the three dimensional object. For this purpose the powdery material is first spread over the working surface and then smoothed into a uniform layer using a wiper or a blade.
In both the first and second approaches the excess powdery material remains on the working surface, but this excess is not needed for solidifying and for producing the three dimensional object.
Powdery materials exhibiting relatively expensive base materials that are available only to a limited degree are typically used in the manufacture of high temperature components, so that it is desirable to use the smallest possible amount of powdery material when producing a three dimensional object.
Exemplary embodiments of the present invention are directed to a more effective device and method for producing a three dimensional object through selective solidification of a powdery material by means of the application of energy.
Exemplary embodiments of the present invention provide a device for producing a three dimensional object from a powdery material by solidifying the powdery material through the application of energy has a working surface, on which the three dimensional object is constructed. Furthermore, the present invention is directed to an application device for applying the powdery material onto the working surface; and there is a solidifying device for solidifying the powdery material applied onto the working surface. In this case the application device for applying the predefined, locally different amounts of powdery material onto the working surface comprises a transfer device, which can be magnetized and/or can be electrostatically charged and discharged and which is designed for transferring the powdery material to the working surface, as well as comprises a magnetizing and/or charging device for the purpose of magnetizing and/or electrostatically charging and discharging the transfer device.
It is known from, for example, the laser printing method to apply toner in a selective manner on the material to be printed at predefined positions by means of an electrostatically charged or magnetized image drum surface. In this case the image drum functions as the transfer device for transferring the toner onto the material to be printed.
At the same time the image drum is uniformly charged and/or magnetized over its entire surface; and then the charge is quenched at defined locations through the application of light. The toner powder is configured in such a way that it is uniformly deposited only on either the charged locations or the neutralized locations.
At this point the transfer device functions, as required, to transfer the powdery material onto the working surface of the device for producing a three dimensional object.
However, in this case the transfer device is not designed to transfer a toner material that has been developed specifically to be deposited in a uniform layer thickness on an image drum that has been either charged or magnetized as required. Rather, the transfer device is designed in such a way that the powdery material, which is configured in its properties not specifically to be deposited on the transfer device, but rather is optimized for producing the three dimensional object with special properties, can be deposited on the surface of the transfer device.
For this purpose there is a magnetizing and/or charging device that can magnetize and/or electrostatically charge and discharge the transfer device as a function of the powdery material that is to be deposited.
Preferably the magnetizing and/or charging device is designed for locally magnetizing and/or for locally electrostatically charging and discharging the transfer device at predefined positions.
As a result, the transfer device can be electrostatically charged or magnetized at very specific positions, so that the powdery material is deposited advantageously only at these positions. It is also possible to configure the magnetization and/or the charging of the transfer device in such a way that the powdery material is deposited on the transfer device not only at locally different positions, but also that different amounts of the powdery material can be deposited in an advantageous way.
An additional advantageous feature lies in the fact that the transfer device is adapted in terms of geometry to the working surface and has, in particular, the same width extension and/or length extension as the working surface.
Consequently the transfer device with the deposited powdery material can be easily arranged preferably over the working surface and can be demagnetized or discharged, so that the powdery material falls in an advantageous manner directly on the desired positions on the working surface. Hence, a lateral movement of the transfer device parallel to the working surface can be dispensed with in this advantageous way.
It is especially preferred that the transfer device be formed by means of a roller and/or by means of a plate.
A design in the form of a plate has the advantage that the transfer device has to be moved only over the working surface; and the powdery material can be applied preferably without movement in additional spatial directions.
A roller has the advantage that the rolled-up surface that transfers the powdery material can advantageously reduce the space requirement in the entire system.
To this end it is advantageous for the roller to have a circumference that corresponds to the width extension of the working surface in the rolling direction of the roller.
As an alternative, the plate and/or the roller can also be constructed so as to be shorter or rather narrower than the working surface, or more specifically the roller can have a smaller circumference than the width extension of the working surface. This feature has the advantage that the transfer device can be constructed preferably small and, as a result, can reduce in an advantageous way the space requirement. Then there are a number of steps for carrying out the transfer of a layer of the powdery material onto the entire working surface.
Preferably a supply device for storing the powdery material that is to be placed onto the working surface is provided.
Then the transfer device can receive in an advantageous way from the supply device the desired amount of powdery material at the desired positions and can then transfer this powdery material onto the working surface.
If, in addition, the supply device has the same length and/or width extension as the transfer device and/or the working surface, then the transfer of the powdery material from the supply device onto the working surface is preferably extremely simple, because only the transfer device is arranged preferably over and/or in the supply device, in order to receive the powdery material; and then a layer of the powdery material can be applied advantageously onto the working surface in one step.
As an alternative, however, the transfer device, the working surface and the supply device can also have different dimensions. This difference can be balanced in an advantageous way by means of the transfer device, if this transfer device can be guided preferably laterally over the supply device and/or the working surface, or if this transfer device is constructed in terms of geometry to match.
It is particularly preferred that the magnetizing and/or charging device be configured for magnetizing and/or charging a transfer device, which is arranged in and/or over the supply device, at predefined positions and for demagnetizing and/or discharging the transfer device, which is arranged on and/or over the working surface, at predefined positions.
As a result, two alternative transfer methods for transferring the powdery material from the supply device onto the working surface can be carried out in an advantageous way.
Either the transfer device is completely coated with the powdery material and allows powdery material to fall onto the working surface by selectively demagnetizing and/or selectively discharging on and/or over the working surface preferably only at predefined positions.
As an alternative, however, the transfer device can also receive the powdery material only at predefined positions of its own surface; and then the powdery material is allowed to fall onto the working surface.
In the event that a roller is used, the roller is mounted over the supply device and/or the working surface in such a way that said roller can be rotated in an advantageous way.
As a result, the roller can be rotated over the supply device and/or the working surface, so that in this way said roller can advantageously receive and dispense in a space saving way the powdery material.
Preferably a motion device for moving the transfer device between the supply device and the working surface is provided.
As a result, the transfer device can be moved back and forth between the supply device and the working surface; and, hence, the powdery material can be transported in an advantageous way from the supply device onto the working surface.
It is particularly preferred that the motion device be designed for moving the transfer device in three spatial directions and/or for rotating and/or pivoting the transfer device.
The more movable the motion device, the more space can be saved preferably in the entire system.
Then in the case that the motion device can move back and forth only between the supply device and the working surface, it is advantageous for the transfer device and also the supply device to be adapted in terms of geometry exactly to the working surface.
If, however, the motion device can also move the transfer device in additional spatial directions and can also rotate or more specifically can pivot said transfer device, then the supply device and/or the transfer device can also be designed with significantly smaller dimensions than the working surface, so that preferably space in the entire system can be saved.
The method is carried out advantageously not only essentially horizontally to the working surface but also essentially vertically thereto. In particular, the method can be carried out in all directions between the horizontal direction up to the vertical direction to the working surface. For example, the transfer device can be tilted into the vertical plane from the horizontal plane, so that the transfer device can be oriented essentially between horizontally up to vertically to the working surface, when the powdery material is applied and/or when the transfer device is moved over the working surface. In this case the powdery material can be applied at individual predefined positions or at a plurality of predefined positions. Hence, the rate of time required to complete a three dimensional object decreases.
Preferably a control unit is provided for controlling the magnetizing and/or charging device and/or the motion device and/or the solidifying device.
Depending on how the desired layer is supposed to look, the control unit can control preferably, as required, the magnetizing and/or charging of the transfer device and can also control advantageously, as required, the motion device to the effect that said control unit moves the transfer device to the desired positions. In addition, the control unit can also actuate in an advantageous way the solidifying device that then solidifies the powdery material that is applied onto the working surface.
Preferably the control unit comprises a memory unit that has stored in an advantageous way a construction plan with the desired final contour of the three dimensional object. The construction plan can be stored, for example, in the form of 3D CAD data. Then the control unit can control in an advantageous way, as a function of the construction plan data stored in the memory unit, the motion device, the magnetizing and/or charging device, the solidifying device and/or the working surface, so that the three dimensional objects can be produced preferably according to the stored construction plan.
The solidification of the powdery material can be implemented, for example, by electromagnetic radiation, such as a laser beam. In this case a laser beam is advantageously guided by the control unit, preferably guided selectively by means of an optical device, such as a mirror arrangement, to predefined positions, onto which the powdery material has been applied selectively by means of the transfer device.
As an alternative, it is also possible to use an electron beam, instead of electromagnetic radiation. It is also conceivable to solidify the selectively applied powdery material preferably by intensive applications of heat. When the powdery material is applied essentially between the horizontal direction up to the vertical direction, the optical system can be advantageously aligned in such a way that a laser beam, an electron beam or the beam of a heat source impinges horizontally or obliquely on the powdery material to be solidified.
The working surface is adjustable up and down in the advantageous embodiment.
As a result of this vertical adjustability, the working surface can be lowered by a predefined path after each solidification step, in order to be able to apply in this way the next layer of the powdery material on the working surface at the same level as during the previous step. For example, this feature also makes it possible to dispense advantageously with a height adjustment of the transfer device by means of the motion device.
In a method for producing a three dimensional object from a powdery material by means of selective solidification through the application of energy, the object is produced layer by layer in such a way that in each case a layer of the powdery material is applied and solidified on a working surface. In order to apply the layer of powdery material, the following steps are carried out:    a) positioning a transfer device for applying the powdery material on the working surface over or in a supply device;    b) magnetizing and/or electrostatically charging the transfer device, so that the powdery material is deposited on the transfer device;    c) moving the transfer device on or over the working surface;    d) demagnetizing and/or discharging the transfer device, so that the powdery material falls onto the working surface at predefined points.
Following the demagnetizing and/or discharging of the transfer device, the powdery material is advantageously scraped off with a blade.
The transfer device is advantageously magnetized and/or electrostatically charged in a selective manner at predefined positions either over and/or in the supply device or on and/or over the working surface.
Following the selective solidification of the powdery material, the working surface is preferably lowered; and an additional layer of the powdery material is applied.